"We weren't sure they could survive that long, but we thought potentially they could," Olssen-Francis told Discovery News.
It turned out they could. When the little rock chips containing the bacteria were brought back to Earth and placed in a liquid solution, the bacteria were rejuvenated and filled the glass tubes with blue-green blooms.
These bugs are used to living in tough environments. Clinging to the limestone cliffs of Beer, they have to withstand salt water, radiation and dry spells.
Cyanobacteria have also colonized many other hostile places, including Antarctica, the African soda lakes and the boiling hot springs of Yellowstone National Park.
Several factors help make cyanobacteria tenacious, says Igor Brown, an astrobiologist who has researched this type of photosynthesizing bacteria for NASA.
When these bacteria are faced with an adverse environment, say outer space, they exude a gel-like covering -- a biopolymer -- that protects them from drying out. All their biological processes slow down, until they are barely, just barely alive, Brown says.